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Measuring contact angles in the field: Protocol

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Motivation:

When solar photovoltaic panels have already been deployed in the field, there might be a need to measure the surface properties of their encapsulating glass. This page lists out three ways of measuring contact angle of rain water on glass with different coatings in order of preference.

Method 1 (Preferred method):

1. Coat panel encapsulation glass with chosen coating. Using the same process coat a glass microscope slide with the same chosen coating.

2. Use contact angle measurement setup and program as described here.

Method 2:

1. Coat panel encapsulation glass with chosen coating. Using the same process coat a glass microscope slide with the same chosen coating.

2. Using a graduated syringe positioned to drop water exactly normal to the surface, release a droplet of volume 10-30 microliters on the glass slide.

3. Take an image of the droplet on this surface and use imageJ plugin for contact angle measurements to find the angle.

Method 3:

This method should only be used for field testing.

1. Coat panel encapsulation glass with chosen coating.

2. Carefully measure the angle of the solar panel against a flat ground.

3. Using a graduated syringe positioned to drop water exactly normal to the surface, release a droplet of volume 10-30 microliters on the glass encapsulation.

4. Position your camera on a tripod and take a picture of this droplet.

5. Measure both receding and advancing contact angles on the substrate using the imageJ plugin.